CN104107920B - The continuous directional solidifying method for preparing of in-situ preparation nano-particle copper-ferroalloy - Google Patents

Abstract

The invention belongs to the field of metal materials, and relates to a continuous directional solidification preparation method for in-situ generation of nano-particle copper-iron alloy. The process is to clean the raw materials and place them in a graphite crucible, vacuumize the vacuum melting furnace to 10 ^‑3 Pa, and then start heating and melting. After the raw materials are completely melted, high-purity argon gas is introduced to keep the melt temperature at 1200°C±5°C～1300°C±5°C, and the cooling system is turned on at the same time. The cooling water volume is 900L/h. ‑3mm/10s casting speed to prepare billets. The technology involved in the present invention can directly produce in-situ nanoparticles that are coherent or semi-coherent with the collective interface in the process of continuous directional solidification, and these nanoparticles are uniformly dispersed in the matrix.

Description

In situ generation of nanoparticle copper - Preparation method of continuous directional solidification of ferroalloy

technical field

The invention belongs to the field of metal materials and relates to a continuous directional solidification preparation method for in-situ generation of nano particle Cu-Fe alloy.

Background technique

Nano-block metal materials have high strength, but their elongation is low. Nano-particle dispersion-strengthened metal materials can greatly increase the strength of the alloy while maintaining the elongation of the alloy, and its strengthening effect is better than that of traditional The micron-scale and sub-micron-scale second-phase particle dispersion strengthening used in metal materials, and the study of nano-disperse phase-strengthened alloys have become a hot spot in recent years. Nano-strengthening can not only greatly improve the strength of metal materials, but also improve the high-temperature creep properties of superalloys. Nanostrengthening technology has important application value for metal materials used in a wide range of fields such as automobile industry, shipbuilding industry, and electric power industry.

At present, the nano-scale strengthening phases in metal materials are all obtained through plastic deformation and heat treatment. However, there are few reports on obtaining the in-situ precipitated nano-dispersion strengthening phase directly in the tissue through directional solidification.

Cu-Fe is a typical liquid immiscible alloy, in the literature [C. P. Wang, X. J. Liu, I. Ohnuma, R. Kainuma,* K. Ishida. Formation of Immiscible Alloy Powders with Egg-Type Microstructure, science, 297,990(2002)] pointed out that even under microgravity conditions, it is difficult to obtain a uniform and dispersed microstructure for liquid-phase immiscible alloys.

In recent years, the inventor has carried out in-depth basic research on the precipitation of nano-phases in the alloy solidification process, and some research results can be found in [Zidong Wang, Xuewen Wang, Qiangsong Wang, I Shih and J J Xu. Fabrication of a nanocomposite from in situiron nanoparticle reinforced copper alloy, Nanotechnology, 2009, 20:075605]. The preliminary conclusion we have obtained is: the alloy melt formed by the dissolution of high-melting-point precipitated phase atoms in the low-melting point metal, its solubility decreases with the decrease of temperature, from the melt temperature to the solidification temperature, relative to the melting point of the precipitated phase, the precipitated phase A large degree of supercooling is obtained, the nucleation radius is extremely small, and nanoscale precipitated particles can be formed.

Applying this theoretical basis, we prepared Cu-Fe alloys by continuous directional solidification technology, and obtained in-situ-generated Fe nanoparticles with uniform and dispersed distribution.

Contents of the invention

The purpose of the invention is to prepare Cu-Fe alloy by using continuous directional solidification technology, and obtain in-situ generated nano-Fe particles with uniform dispersion distribution.

The technical solution adopted in the present invention is: a continuous directional solidification preparation method for in-situ generation of nano-particle Cu-Fe alloy. In this method, the raw materials are cleaned and removed and placed in a graphite crucible, and the vacuum melting furnace is evacuated to 10 ^-3 After Pa, start heating and smelting. After the raw materials are completely melted, high-purity argon gas is introduced to keep warm and the cooling system is turned on at the same time to adjust the amount of cooling water. During the pull-down process of the lead rod, the top of the crystallizer is heated by the metal melt and the surrounding crucible, the upper part of the side is kept warm by the heat preservation device, and the lower part and the bottom are cooled by wet cold air or cooling water to form a temperature with a certain temperature gradient. At the same time, under the comprehensive influence of the heating of the top melt, the cooling of the bottom cooling water, and the crystallizer with a temperature gradient, the nucleation on the wall of the crystallizer is inhibited and a vertical temperature gradient is formed. During the solidification process, the solid-liquid interface is kept in the middle of the crystallizer. Due to the self-solidification and shrinkage of the metal, the solidified metal is automatically separated from the crystallizer wall to avoid friction, and finally realizes continuous directional solidification of the metal. In the directional solidification process, the alloy melt formed by the high melting point precipitated phase atoms dissolving in the low melting point metal, its solubility decreases with the decrease of temperature, from the melt temperature to the solidification temperature, relative to the melting point of the precipitated phase, the precipitated phase is obtained With a large degree of undercooling, the nucleation radius is extremely small, and nanoscale precipitated particles can be formed.

Process of the present invention:

Step 1: According to the mass percentage of each alloy composition is Fe: 0.5-2%, and the rest is Cu, respectively weigh Cu and Fe, clean and remove impurities, and place them in a graphite crucible, place the graphite crucible in a vacuum induction furnace, and put After the vacuum induction furnace is evacuated to 10 ^-3 Pa, heat it to a temperature of 350°C, keep it warm for 20 minutes and dry it. After drying, evacuate the vacuum induction furnace to 10 ^-3 Pa again, and discharge the gas;

Step 2: Raise the temperature to 1200-1250°C to completely melt Cu and Fe, then inject high-purity argon and keep it warm for 30 minutes to obtain an alloy melt for later use;

Step 3: Keep the temperature at 1200°C±5°C～1300°C±5°C, turn on the cooling system, adjust the cooling water volume to 900L/h, adjust the casting speed to 1.5-3mm/10s, turn on the traction system, and the billet After being pulled by the pulling equipment, the continuous production of nano-particle Cu-Fe alloy material is realized.

The beneficial effects of the present invention are: due to the adoption of the above technical scheme, in-situ nanoparticles that are coherent or semi-coherent with the collective interface are directly produced in the continuous directional solidification process realized by the present invention, and these nanoparticles are uniformly dispersed in the matrix . The nano particle Cu-Fe alloy material prepared by the invention has good mechanical properties, the tensile strength reaches more than 179MPa, and the elongation remains above 40%.

Description of drawings

Fig. 1 is the TEM photograph of the nano-morphology of the Cu-Fe alloy obtained in the as-cast state of the present invention.

Fig. 2 is the HRTEM photo and diffraction spots of Fe nanoparticles obtained in the cast state of the present invention.

detailed description

The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

Example 1

The mass percentage of copper alloy composition in this experiment is (98%) Cu, (2%) Fe.

Step 1: After cleaning and removing impurities, the raw materials are placed in a graphite crucible, the vacuum induction furnace is evacuated to 10 ^-3 Pa, and the temperature is set at 350°C, heated to the set temperature and then kept for 20 minutes for drying. After drying, evacuate the vacuum induction furnace to 10 ^-3 Pa again to discharge the gas;

Step 2: Evacuate the vacuum induction furnace to 10 ^-3 Pa and raise the temperature to 1225°C to heat and melt. After the metal raw material is completely melted, introduce high-purity argon, keep it warm for 30 minutes and turn on the cooling system;

Step 3: Adjust the cooling water volume to 900L/h, adjust the casting speed to 1.5mm/10s, and then turn on the traction system. Observe the melt temperature during the casting process to ensure that the temperature is kept at 1250°C ± 5°C.

Step 4: The billet is pulled by the traction equipment to realize continuous production;

The prepared Cu-Fe alloy rod has a tensile strength of 195MPa and an elongation of 44%. Under the same experimental conditions, the pure copper rod has a tensile strength of 131MPa and an elongation of 43%. From the comparison results, it can be found that the tensile strength of the Cu-Fe alloy rod is greatly improved compared with the pure copper rod, and the elongation is also slightly improved.

Example 2

The mass percentage of copper alloy composition in this experiment is (99.5%) Cu, (0.5%) Fe.

Step 1: After cleaning and removing impurities, the raw materials are placed in a graphite crucible, the vacuum induction furnace is evacuated to 10 ^-3 Pa, and the temperature is set at 350°C, heated to the set temperature and then kept for 20 minutes for drying. After drying, evacuate the vacuum induction furnace to 10 ^-3 Pa again to discharge the gas;

Step 2: Evacuate the vacuum induction furnace to 10 ^-3 Pa and raise the temperature to 1250°C for heating and melting. After the metal raw material is completely melted, introduce high-purity argon gas, keep it warm for 30 minutes and turn on the cooling system;

Step 3: Adjust the cooling water volume to 900L/h, adjust the casting speed to 3mm/10s, and then turn on the traction system. Observe the melt temperature during the casting process to ensure that the temperature is kept at 1250°C ± 5°C.

Step 4: The billet is pulled by the traction equipment to realize continuous production;

Example 3

The mass percentage of copper alloy composition in this experiment is (99%) Cu, (1%) Fe.

Step 1: After cleaning and removing impurities, the raw materials are placed in a graphite crucible. After the vacuum induction furnace is evacuated to 0.001Pa, the temperature is set at 350°C, heated to the set temperature, and then kept for 20 minutes for drying. After drying, evacuate the vacuum induction furnace to 0.001Pa again to discharge the gas;

Step 2: Vacuumize the vacuum induction furnace to 0.001Pa and raise the temperature to 1200°C to heat and melt. After the metal raw material is completely melted, introduce high-purity argon, keep it warm for 30 minutes and turn on the cooling system;

Step 3: Adjust the cooling water volume to 900L/h, adjust the casting speed to 2.5mm/10s, and then turn on the traction system. Observe the melt temperature during the casting process to ensure that the temperature is kept at 1300°C ± 5°C.

Step 4: The billet is pulled by the traction equipment to realize continuous production;

The prepared Cu-Fe alloy rod has a tensile strength of 179MPa and an elongation of 40%. Under the same experimental conditions, the pure copper rod has a tensile strength of 131MPa and an elongation of 43%. From the comparison results, it can be found that the tensile strength of the Cu-Fe alloy rod is greatly improved and the elongation is slightly decreased compared with the pure copper rod.

Claims (1)

1. the continuous directional solidification preparation method of in-situ generation nano particle copper-iron alloy, it is characterized in that, the method comprises the following steps: Step 1. According to the mass percentage of each alloy composition is Fe: 0.5-2%, and the rest is Cu, respectively weigh Cu and Fe, clean and remove impurities, and place them in a graphite crucible, place the graphite crucible in a vacuum induction furnace, and put After the vacuum induction furnace is evacuated to 10 ^-3 Pa, heat it to a temperature of 350°C, keep it warm for 20 minutes and dry it. After drying, evacuate the vacuum induction furnace to 10 ^-3 Pa again, and discharge the gas; Step 2: Raise the temperature to 1200-1250°C to completely melt Cu and Fe, then inject high-purity argon and keep it warm for 30 minutes to obtain an alloy melt for later use; Step 3: Keep the temperature at 1250°C ~ 1300°C, turn on the cooling system, adjust the cooling water volume to 900L/h, adjust the drawing speed to 1.5-3mm/10s, turn on the traction system, and the billet is pulled by the traction equipment, The continuous production of in-situ generation nano-particle Cu-Fe alloy material is realized.